More People are Killed or Wounded in Active Shooter Incidents Involving Semiautomatic Rifles

More People are Killed or Wounded in Active Shooter Incidents Involving Semiautomatic Rifles
September 13, 2018 Center for Surgery and Public Health

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Through analysis of available data, BWH researchers identify lethality of civilian active shooter incidents, make case for national firearm injury database

Boston, MA — Semiautomatic rifles have been used in some of the largest active shooter incidents in U.S. history. Responding to a lack of available information on the lethality of these weapons, researchers from the Center for Surgery and Public Health (CSPH) at Brigham and Women’s Hospital compared the number of persons wounded and/or killed during active shooter incidents with and without semiautomatic rifles. Their findings are published in a research letter this week in JAMA.

Since 2000, the Federal Bureau of Investigation (FBI) has tracked active shooter incidents, which it defines as a situation in which an individual is actively engaged in killing or attempting to kill people in a confined or populated area. While this publicly accessible database is the most comprehensive available, and includes information on shooter demographics, location, number of people wounded and/or killed, and type of firearm present (rifle, shotgun, handgun), it does not indicate whether a rifle was semiautomatic.

“In order to inform the debate on semiautomatic rifles, commonly referred to as assault rifles, we needed to understand their lethality,” said Eric Goralnick, MD, MS, medical director of Emergency Preparedness, emergency medicine physician at Brigham and Women’s Hospital and one of the authors of the study. “We chose active shooter incidents because a national firearm injury database is currently unavailable.”

To determine the presence of a semiautomatic rifle in an active shooter incident, CSPH researchers performed a media content analysis, establishing an a priori search hierarchy in which the primary data sources were court and police documents or witness statements (45.5 percent; 35 of 77), and secondary data sources were contemporaneous news articles. For incidents relying upon media reports to confirm the presence of a semiautomatic rifle, a minimum of three articles from different media outlets was required to triangulate the data. All incidents with the presence of a semiautomatic rifle were classified as semiautomatic rifle incidents regardless of other firearm presence. Two incidents, the Las Vegas shooting, which represented a statistical outlier, and the San Bernardino, California, shooting, which had more than one shooter present, were excluded. The research team used a negative binomial regression to estimate the association between the presence of a semiautomatic rifle and the total numbers of nonfatally wounded, killed, and wounded or killed, and the percentages of persons who died if wounded at the incident. They controlled for the place and year of the shooting and the presence of other firearms.

“Semiautomatic rifles don’t make you more likely to die if you get shot,” said Adil Haider MD, MPH, a trauma surgeon and Kessler Director of the Center for Surgery and Public Health at BWH, and lead author of the study. “What they do is allow active shooters to shoot twice as many people, leading to twice as many people wounded or killed.”

Of the 248 active shooter incidents recorded by the FBI as of publication, resulting in 898 persons wounded and 718 killed, 24.6 percent (61) involved a semiautomatic rifle and 75.4 percent (187) involved handguns, shotguns, and non-semiautomatic rifles. Multiple firearm types were recorded in 60.7 percent of the semiautomatic rifle incidents. The presence of a semiautomatic rifle was associated with a higher incidence of persons wounded (5.48 vs. 3.02), killed (4.25 vs. 2.49), and wounded or killed (9.72 vs. 5.47).

CSPH researchers found that although 44 percent of persons wounded in active shooter incidents died from their injuries, irrespective of the type of firearms used, more people were wounded and killed in incidents where semiautomatic rifles were used compared with incidents involving other firearms. Semiautomatic rifles are designed for easy use, can accept large magazines, and fire high-velocity bullets, enabling active shooters to wound and kill more people per incident. Lack of data, including information on specific injuries, makes it difficult to fully explain the association and points to the need for a national centralized database to inform the debate on a renewed assault weapons ban.